If the link doesn't work - to to http://www.nortelnetworks.com and navigate to Technical Support/Baystack 425-24T Switch/Document Detail Information/Using the Baystack 420/225 Switch, Software Relase 3.1

Stack configurations
As shown in Figure 9, the cable connectors provide the ability to stack up to eight
switches. Because stack parameters are associated with the base unit (see “Base
unit” on page 62), the physical stack order depends on the base unit’s position and
whether the stack is configured stack up or stack down.
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Stack up configurations
In Figure 9, data flows from the base unit (unit 1) to the next switch, which is
assigned as unit 2, and continues until the last switch in the stack is assigned as
unit 8. The physical order of the switches is from bottom to top (unit 1 to unit 8).
Figure 9 Stack up configuration example
Table 9 describes the stack up configuration illustration references.
Table 9 Stack up configuration description
Item Description
1 Last unit
2 Base unit
3 Stacking cable 30 cm (order number AL 2018005)
4 Stacking cable 1 m (order number AL 2018006)
2
1 Unit 8
Unit 7
Unit 6
Unit 5
Unit 4
Unit 3
Unit 2
Unit 1
Cascade
Down Up
Cascade
Down Up
Cascade
Down Up
Cascade
Down Up
Cascade
Down Up
Cascade
Down Up
Cascade
Down Up
Cascade
Down Up
Up
Down
11115EA
4 3
Chapter 2 Network configuration 65
Using the BayStack 420/425 Switch, Software Release 3.1
Stack down configurations
In Figure 10, data flows from the base unit (unit 1) to the next switch, which is
assigned as unit 2, and continues until the last switch in the stack is assigned as
unit 8. The physical order of the switches is from top to bottom (unit 1 to unit 8).
Figure 10 Stack down configuration example
Table 10 describes the stack down configuration illustration references.
Table 10 Stack down configuration description
Item Description
1 Base unit
2 Last unit
3 Stacking cable 30 cm (order number AL 2018005)
4 Stacking max-return cable 1 m (part number AL 2018006)
Unit 1
Unit 2
Unit 3
Unit 4
Unit 5
Unit 6
Unit 7
Unit 8
1
10002EA
4
100-240 V-
50-60Hz 2A
Out In
Cascade
2
100-240 V-
50-60Hz 2A
Out In
Cascade
100-240 V-
50-60Hz 2A
Out In
Cascade
100-240 V-
50-60Hz 2A
Out In
Cascade
100-240 V-
50-60Hz 2A
Out In
Cascade
100-240 V-
50-60Hz 2A
Out In
Cascade
100-240 V-
50-60Hz 2A
Out In
Cascade
100-240 V-
50-60Hz 2A
Out In
Cascade
In
Out
3
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Certain network management station (NMS) applications assume a stack down
configuration for the graphical user interface (GUI) that represents the stack (see
Figure 10). For this reason, Nortel Networks recommends that you always
configure the top unit in the stack as the base unit.
In any stack configuration, the following applies:
• When you apply power to the stack, the base unit initializes and the entire
stack powers up as a single logical unit.
• You can attach an RS-232 communications cable to the console port of any
switch in the stack.
• You can downline upgrade the entire stack from any switch in the stack from
the console interface, a Telnet session, the Web-based management interface,
or any generic SNMP-based network management software.
• You can access and manage the stack using a Telnet connection, the
Web-based management interface, or any generic SNMP management tool
through any switch port that is part of the stack configuration.
• When you stack three or more switches, use the longer (1-meter) stacking
max-return